1. Field of the Invention
The present invention relates to a semiconductor device, particularly a semiconductor device including a thin film semiconductor element, and a manufacturing method thereof.
2. Description of the Related Art
In general, a current mirror circuit is used in many cases as part of a power supply circuit of a display or the like. The power supply circuit includes an analog circuit, and the performance of a bias circuit is important as the stable operation. It is important to design a bias circuit in a case of designing a high-performance analog circuit or a low-voltage operation circuit.
In conventional amplifier circuits, there are some of them, the performance of which is improved by multistage connection of thin film transistors (TFTs) (for example, see Patent Document 1: Japanese Published Patent Application No. H6-37558).